Virology

Molecular Testing – Chlamydia Trachomatis (SDA/NAAT)

Preferred sample for urogenital Chlamydia Trachomatis infection is a self or clinician-taken low vaginal swab for women and first-catch urine for men or women. Endocervical and urethral swabs can also be tested.

Vaginal/endocervical swab samples for Chlamydia examination

Obtain sampling kit from Virus Laboratory, Castle Hill Hospital or specimen reception. Instructions enclosed with kit.

Urine samples for Chlamydia examination

Patients should hold their urine for at least one hour before collection of the specimen. A first voided urine (the first 15-20ml) should be collected in a 25ml Universal (NOT the Boric acid MSU container) or 60ml polypot and kept refrigerated prior to transport to the laboratory. Specimens should arrive at the laboratory within 48 hours of collection.

The collection vessel used is particularly important.

  • It must not have a metal lid or be collected initially into a metal foil bowl as metal ions can interfere with the test.
  • It must not be cardboard as the fibres can leach into the sample and cause blockage of equipment and interference with the test.

Conjunctival swab for Chlamydia examination

Obtain swab (purple top) from Virus Laboratory, Castle Hill Hospital. Wipe conjunctival discharge away with sterile swab, then gentle rub swab along lower conjunctival sac. The discharge contains few chlamydia so the swab is intended to collect conjunctival cells which have better yield. Please wait until after Chlamydia swab has been taken before applying fluorescein to the eye, as if the swab has fluorescein on it this interferes with the test process.